Digital optical disks are now being seriously considered as potential alternatives to magnetic tape and disk memories. It has been found that optical disks offer a substantially greater data storage capacity than commercially available magnetic tape or disc memories of similar size.
As is well known, digital optical disks are configured to have a plurality of tracks. A continuous, spirally configured track format is well suited for applications involving long, continuous runs of digital data, while a format providing a plurality of concentric tracks may sometimes be better for applications requiring random access to selected memory locations. By synchronizing movement of the laser optics with rotation of the optical disk, desired tracks and track regions of the optical disk can be accessed for writing or reading purposed. Conventionally, movement of the laser optics is achieved by traversing a carriage containing the laser optics along a linear path across the tracks, as taught by U.S. Pat. Nos. 3,969,344 and 3,720,924, or by moving the optical disc along a linear path in conjunction with stationary laser optics, as taught by U.S. Pat. No. 3,438,050. Since optical disks and laser optics are not particularly light weight (compared with magnetic disk heads), and thus, have relatively large inertia, the access times for optical disks are usually slow. Conventionally, faster access times for optical disks are achieved by utilization of large drive motors which are expensive. Also, movement of the laser optics may produce vibration of the laser optics. Accordingly, there is a need for apparatus that can achieve fast accessing of an optical disk without utilizing a large drive motor, and that is substantially free of laser optics vibration.